Regulation of endothelin-1 gene expression by cell shape and the microfilament network in vascular endothelium

Endothelial synthesis and release of endothelin-1 (ET-1) are exquisitely regulated by external shear and strain. We tested the hypothesis that manipulation of endothelial cell shape can regulate ET-1 gene expression. Treatment of bovine aortic endothelial cell (BAEC) monolayers with cytochalasin D disrupted F-actin and induced cell retraction and rounding, in parallel with time- and dose-dependent specific decreases in ET-1 mRNA levels. Treatments with forskolin, phorbol 12-myristate 13-acetate, staurosporine, and genistein also induced cell shape change and decreased F-actin staining and ET-1 mRNA levels. BAEC plated onto nonadhesive petri dishes coated with decreasing concentrations of synthetic RGD polymer showed RGD dose-dependent decreases in cell spreading and in F-actin microfilament elaboration. These changes were specifically accompanied by decreases in ET-1 peptide secretion (60%) and, via posttranscriptional mechanisms, ET-1 mRNA (94%) and were not due to decreased cell-cell contact. We conclude that the shape and microfilament network of endothelial cells are potent posttranscriptional regulators of ET-1 gene expression.